Engineering silicon detectors with high quantum efficiency for low energy electrons

Numerous precision metrology systems for detecting quanta of any kind are based on silicon detectors. One example are silicon detectors used in scanning electron microscopes (SEM) for electron detection. The need to investigate objects at the very near surface like e.g. cells in biology pushes the scientific progress for these silicon detectors. To study surface near regions of e.g. biological objects electrons with low energies around 500eV are necessary. Unfortunately, the quantum efficiency for such low energy electrons of state-of-the-art electron detectors is low or even non-existent. In this contribution the development of silicon electron detectors with large quantum efficiencies of more than 55% for electrons with an energy of 500eV is presented. The crucial steps in the development like the thin entrance window and a very shallow junction will be discussed and analyzed by simulation and experiments like secondary ion mass spectrometry (SIMS) measurements at CiS.